Are Runners Usually Underweight or Thin? (3 Reasons To Consider)

If you’ve ever watched a running sporting event, you may notice that the athletes are typically underweight or very thin. Unlike other athletic pursuits, running builds lean muscle instead of bulky muscle, which gives these athletes a skinny appearance.

Runners are typically thinner than other athletes and may even appear underweight because of the number of calories burned while running and the development of lean rather than bulky muscles in both the legs and core. Despite the caloric burn of a good run, runners also experience a decreased appetite meaning they rarely take in the calories used.

Keep reading to learn more about what makes many runners appear thin or even underweight.

Is it normal or healthy for runners to appear underweight?

I’m sure you are familiar with the typical “runner’s body” – very slim with small, tight leg muscles and smaller arms – but what causes this easily identifiable combination of low body fat and specific muscular development?

It’s common for runners to push themselves too hard and over-train their bodies. When runners over-train, they have trouble maintaining their appetite, which can lead to additional weight loss.

Around 60% of runners experience overtraining at some point. In rare cases, this practice can lead to overtraining syndrome, which is difficult to diagnose but can greatly impact running performance and overall health. 

Additionally, runners can put extra stress on themselves, especially in regard to their running. Stress on its own can mess with your metabolism and lead to weight-related issues. For some people, these weight-related issues mean gaining weight, but for runners, it typically means losing weight.

What is a runner’s average weight?

Runners tend to be below the average weight of healthy non-runners because of reasons we’ll detail below, but it can be hard to nail down a specific number because of a wide range of factors including height and gender.

A serious runner is likely to fall within the ideal goal weight for their age, height, and gender and may be more likely to track BMI instead (although that’s not a perfect solution either. For example, the ideal average weight for a 6′ tall man is 158.4 lb, but he’s can go as low as 135 lb before he’s considered underweight.

There are several ways to determine your ideal running weight and it’s safe to assume that most serious runners will try to make that goal in order to maximize their times. The most common methods are:

  • The Competitive Runner’s Handbook – In this book, Bob and Shelley Glover gave a fairly simplistic guide for finding a runner’s ideal weight. This method varies by gender, but suggested that a 6′ male runner should be 148-168lb while a 5’6″ female runner should be 110-130 lb.
  • Stillman Weight Tables – While this method is becoming increasingly outdated, it’s still a classic and a go-to for many. For this method, you start with a standard ideal weight for non-runners and subtract a percentage based on the type of running you do with sprinters staying closest to the average and long-distance runners dropping as much as 15% of the average weight.
  • BMI – BMI is classified as “normal” at 18.5-25; however, athletes and runners in particular tend to be on the lower end of that range. Runners whose BMIs drop below 18.5 are considered underweight.

Are professional runners underweight?

Professional athletes are the peak example of the body sculpted by their sport, and with their sinewy legs, and almost impossible flat stomachs, runners are no exception.

Most professional marathon runners are underweight because they burn tons of calories while they train. Runners strive to carry as little extra weight as possible to avoid expending extra energy during the run.

The following are some of the most popular runners in the world and how much they weigh so that you can get an accurate reference:

Weighing less than average is also a great way for professional runners to boost their performance. Having less weight to carry allows them to conserve their energy more than we cut it if they were heavier. 

Does running make you skinny?

Most runners on a professional and casual level are skinny. This exercise is known to help people shed weight quicker than other forms of exercise.

Running makes people skinny because:

  • Burns calories
  • Suppresses appetite
  • Exercises your core

Let’s take a look at each of these and see how they contribute to the overall skinny appearance of regular runners.

Burns calories

The main reason running makes people skinny is that it burns calories.

If you run nonstop for an hour, you’ll burn a minimum of 500 calories. The pace you run determines how many calories you burn, so it can be different for everybody. Even a short run can make a significant impact on the overall caloric burn of your day.

Another aspect that determines how many calories you burn is your weight. The more you weigh, the more calories you burn when you run. 

Suppresses appetite

Another reason running makes you skinny is that even while burning so many calories, it can suppress your appetite. 

While many physical activities lead to you feeling more hungry afterward, running can actually make you less hungry for a time so you’re unlikely to compensate for the burned calories by binge eating directly after your run.

When you’re running regularly, you either need to consciously increase your caloric intake or you’ll lose weight quickly. While this can be great if weightloss is your goal, it can become a health concern if you’re already runner-skinny.

Exercises your core

When you run, you work out every body part, including your core. When you develop your core muscles, you don’t have to worry as much about belly fat.

This is another reason many people believe that runners look skinny. If you run often, you develop lean muscles in your core which helps keep fat away.

Do muscles get leaner after running?

Runners develop lean muscle instead of bulky muscle because leaner muscles preserve more energy during this exercise.

When you run, you train the slow twitch muscle fibers that contribute to lean muscle instead of the large bulky muscles expected from weightlifters. These well-developed slow-twitch muscles help runners complete exercise without getting exhausted.

Running takes plenty of energy, and having bulky, heavy muscles instead of lean muscles can drain your energy. Your body develops muscles depending on the type of exercise you do. If you’re interested in bulking up but still want to run, adding weights to your exercise routine would be best.

However, if you care more about how well you perform while you run, you’ll want to focus on keeping your lean muscle. When you carry more weight around, it’s harder for you to conserve your energy which can affect your running performance. 

What kind of workouts do runners do to appear thin?

Aside from running, many professional runners participate and other exercise routines to enhance their performance.

These exercise routines often make runners appear thin because they focus on improving aerobic performance instead of bulking up:

  • Warm-up runs – Many runners go for a jog before running a big race to help prepare. This is a great way to loosen up the muscles and improve performance. However, this workout also contributes to calorie burning, which makes runners appear thin.
  • Drills – Popular running drills include skips, side-to-side, butt kicks, high knees, and straight-leg running. These drills plenty of calories and tone the core muscles Runners need to increase their speed.
  • Lunges – Although this workout doesn’t burn as many calories as the previous ones, it tones the runner’s legs which helps them look thin. The better runners perform when they run, the more calories they’re likely to burn. So, this training exercise can contribute to run losing weight.
  • Step-ups – This exercise routine tones and conditions the lower body, which runners rely on to burn calories and perform well.